1. Field of the Invention
The present invention relates to a traveling vehicle for operations such as transportation of articles, and particularly to a traveling vehicle including an obstacle sensor to detect obstacles.
2. Description of the Related Art
Conventionally, traveling vehicles such as unmanned carriers include an obstacle sensor which detects obstacles to avoid collisions with them.
For example, an obstacle sensor projects laser light rotationally in various directions and receives light reflected from an object, such as an article, in a path of the traveling vehicle. This allows the traveling vehicle to detect an obstacle within a range in a traveling direction, a distance to the obstacle, and a shape and dimensions of the obstacle, for example.
There are disclosed techniques for control of traveling vehicles using results of detection performed by such object sensors.
For example, according to Japanese Unexamined Patent Application Publication Number 10-161745, a traveling vehicle is decelerated according to a result of detection performed by a proximity sensor on the front of the traveling vehicle. With this, the traveling vehicle may be stopped in a vicinity of another traveling vehicle ahead, so that efficient use of factory space is achieved.
A traveling vehicle for transporting articles may transport an article by traveling along a predetermined path. When an obstacle sensor detects an obstacle in the path while the traveling vehicle is transporting an article, the traveling vehicle decelerates and stops to avoid a collision with the obstacle. As a result, traveling vehicles following the traveling vehicle are forced to stop.
In this case, for example, an operator receives an error notification from the traveling vehicle and goes and removes the obstacle manually. Subsequently, the traveling vehicle and the traveling vehicles following it restart running to resume the interrupted transportation.
In other words, the presence of one obstacle decreases the efficiency of transportation performed by the traveling vehicles.
The traveling vehicle which stops upon detection of an obstacle may perform an avoidance operation (for example, passing by the obstacle) according to a result of detection performed by the obstacle sensor before an operator removes the obstacle to continue transportation.
However, even in the case of such an operation, the traveling vehicles are generally set to travel around a predetermined route repeatedly, so that the traveling vehicles decelerate, stop, and perform an avoidance operation every time they pass the place as long as the obstacle is present in the path.
In addition, in the case where the traveling vehicles are controlled so that transportation may be continued even when there is an obstacle, it is difficult for an operator to safely remove an obstacle. Therefore, a decrease in the overall efficiency of transportation is unavoidable.
Specifically, when there is an obstacle in the path of the traveling vehicle, the obstacle sensor detects the obstacle and a collision of the traveling vehicle with the obstacle is prevented. However, in this case, not only the traveling vehicle but also other traveling vehicles suspend transportation of articles. This operation may cause a great decrease in the efficiency of the transportation performed by the traveling vehicles.